DE 10 2011 015 980 describes a charging station for motor vehicles which is provided with a primary coil unit for inductive transmission of energy to a battery of a motor vehicle and with a metal detector. The metal detector in this case serves to detect metallic objects in a coupling region between the primary coil unit and a secondary coil unit of a motor vehicle. If metallic objects are detected by means of the metal detector, for example a warning can be triggered and the transmission of power, in particular of high-voltage current, to the primary coil element can be prevented.
DE 10 2009 033 236 A1 describes a device for inductive transmission of electric energy. The device comprises an apparatus for detecting an object within a space which comprises, at least during an energy transmission, a space located between a primary inductance of the device and a secondary inductance of the motor vehicle. By means of the device it is thus possible to detect foreign bodies in a field region of the primary inductance.
U.S. Pat. No. 5,821,731 A also describes a charging station for motor vehicles. The charging station includes a primary coil for inductively transmitting energy to a secondary coil of a motor vehicle in order to charge a battery of the motor vehicle in this manner. The charging station includes in addition at least one magnetic sensor by means of which the position of the secondary coil unit of a motor vehicle parked in the charging station can be detected.